textproduct: Quad Cities

KEY MESSAGES

- Prolonged period of wet weather continues, with two more rounds of rain through Thursday night. A Flood Watch remains in effect and has been expanded north for excessive rainfall, rising rivers, and potential areal flooding.

- Pleasant early Fall weather this weekend into early next week, with dry conditions and seasonable temperatures.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 224 PM CDT Wed Sep 30 2026

A gloomy and wet last day of September is occurring across the CWA, with low clouds and rain keeping temperatures in the 60s for much of the daylight hours. Rainfall amounts from the 1st round that is now nearing the eastern edge of the forecast area, were in the 1-2" range primarily within the initial flood watch area, with some 2"+ totals at some mesonet sites in Keokuk, Washington, Muscatine, and Cedar counties as of 1pm. These totals fell in an already saturated area from last week's rain resulting in rises on the English, Skunk, Iowa, Cedar, and Des Moines rivers. Additional flood watches and warnings have been issued for locations on these tribs based largely on the forecast QPF in the next 48 hrs. See hydrology section for additional details.

A brief lull or at least a decrease in overall rain amounts is expected late this afternoon/evening before the next round arrives after midnight. Upper low currently over western NM will slowly move east this evening, with its warm moist conveyor belt continually pulling high PW moisture up into the central Plains and into IA. In fact, our 18z DVN sounding recorded a 2.03" PW which is the 9th highest for the month of September! The most recent sounding that is comparable to that value was back on the 00z 9/22/2019 sounding. A very moist environment to say the least for Sept 30th. Diffluent flow aloft and convergence along a theta-e gradient will allow widespread showers and thunderstorms to continue across northern KS/southern NE this evening/overnight spreading eastward over IA. Deep warm cloud depths combined with a strengthening LLJ will allow these storms to be efficient rain producers with moderate-heavy rain likely for several hours at any one location. WPC has continued its moderate ERO for excessive rainfall for areas just west of the CWA, with a slight (level 2 of 4) risk for excessive rain in our area north of a line from Memphis, MO to Galesburg. The question becomes where does this 2nd round of storms layout over the CWA. Most 12z deterministic and ensemble guidance suggests the axis of heaviest rain (another 1-3") will be displaced slightly north of the 1st round, which would be across north central IA into northeast IA. This scenario is favored and if it comes to fruition would be ideal for limiting any significant flash flood/areal flooding concerns. However, if it falls closer to the Hwy 30/I-80 corridor then there would be more urban flooding issues and perhaps even a flash flood threat just prior to the AM commute.

In addition, the 12z HREF/REFS both have a 1-3hr window between 06z-12z tonight with 3hr QPF amounts exceeding 3hr FFG just north of Cedar Rapids. For this reason, have opted to expand the Flood Watch north into the Hwy 20 corridor.

Thursday, rain will be ongoing during the morning hours similar to today with the overall intensity decreasing as LLJ veers off to the east. Highs may struggle to reach 70 degrees once again with extensive cloud cover overhead. The last and final round of rain arrives during the afternoon and evening, likely occurring in our IL counties. Some of the latest guidance coming in suggests the bulk of this round may occur just to our south, which may allow our Flood Watch to be cancelled early.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 224 PM CDT Wed Sep 30 2026

Pleasant early October weather is forecast late Friday through early next week, with dry conditions and seasonable temperatures. Highs in the 60s and lows in the 40s will be seen. A large 1027mb surface high will build into the upper Midwest bringing a drier airmass into the CWA. It will be a fantastic weekend for any outdoor activities! On Monday, ensemble 850mb temps drop into the 4-8C range and as a result we could see some overnight lows dropping into the upper 30s Monday night.

The next chance of rain will come on Wednesday, as a cold front moves through. Moisture will be limited as noted by 1000-500mb RH progs and this could end up just bringing an increase in clouds. This would be good news for farmers wanting their fields to dry out to start planning their harvest.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 624 PM CDT Wed Sep 30 2026

Predominantly MVFR to IFR conditions expected in low clouds, fog, rain/drizzle/showers during the period with pockets of LIFR (KCID/KDBQ) and VFR (KBRL). Anticipate a bout of heavier convective activity arriving later tonight into Thursday morning tied with increasing synoptic scale ascent with negative theta-e lapse rates in the 850-500 mb layer supportive of embedded thunder. A cold front will sag southward across the terminals late Thursday morning through afternoon bringing a wind shift to a northerly direction. Conditions could improve to VFR post-frontal mid to late afternoon Thursday, particularly at KDBQ and KCID.

HYDROLOGY

Issued at 1232 PM CDT Wed Sep 30 2026

Many of the area rivers have not fully returned to normal streamflows after the last rainfall event in mid-September. That leaves them primed for additional flooding where the higher rainfall totals end up over the next couple days, especially along the Iowa and Skunk rivers. Several river watches and warnings have been issued where flooding is most likely to occur. There will also likely be rises along the Mississippi River especially south of New Boston. These river forecasts are largely based on rain that hasn't fallen yet, so the forecasts will likely be adjusted once we see how much rain falls and where the highest amounts are across the area leading to a higher confidence in flood category. Please keep an eye on forecast and updates to flood products in the coming days.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch through late Thursday night for IAZ040>042-051>054- 063>068-076>078-087>089-098. IL...Flood Watch through late Thursday night for ILZ007-009-015-016- 024. MO...None.